I changed the password on my Yahoo account using Thunderbird on my laptop.

What you can change in Thunderbird is the password Thunderbird has remembered for your Yahoo account. By any means, in order to change the password for your Yahoo account login to your account via webmail, and change the password there.

I had to use Yahoo's new account key security mechanism.

Please explain in more detail what you're talking about.

I then changed the password on my tablet via the Yahoo app.

You'd need to explain whether this changed the Yahoo account password (on the server).

I do not want to create a new Yahoo account because my Yahoo ID is used everywhere.

This doesn't make any sense to me either.

Yahoo password not recognised when trying to create a new Thunderbird account

How is the title of your topic related to this anyway?

I am experiencing the very same problem. Following on from the recent Yahoo account hacking report. I have been to my Yahoo account and changed my password there. I have already set Yahoo up to forward all mail to my Thunderbird laptop application (pop3). I then returned to my laptop Thunderbird application and updated the password in my security settings. Now when trying to read mail in my thunderbird app for my Yahoo mail I get no new mail to the Yahoo account inbox. I do get a pop up with this message "Sending of password for user ron_richesse@yahoo.co.uk did not succeed. Mail server pop.mail.yahoo.com responded: (#MBR1212) Incorrect username or password". Do you need any further information to help with this?

Do you need any further information to help with this?

Please start a new topic for your problem. https://support.mozilla.org/questions/new

No never mind, Sorry for trying to use a bit of common sense.

In attempting to read email in my Thunderbird app for my Yahoo mail I get no new mail to the Yahoo account inbox. I do get a pop up with this message "Sending of password for user pandpgai@yahoo.com did not succeed. Mail server pop.mail.yahoo.com responded: (#MBR1212) Incorrect username or password". I reset password on both Yahoo and Tbird. I get the same message. Is there a solution?

Arrem, taxpeter1,

See https://support.mozilla.org/en-US/questions/1140210

Also see https://support.mozilla.org/en-US/questions/1140210

If none of this fixes your problem, please start a new thread. https://support.mozilla.org/questions/new